1. Field of the Invention
The present invention relates to a control for executing calibration in an image forming system including an image forming apparatus and an image processing apparatus that performs image processing on a print job and inputs the processed print job to the image forming apparatus.
2. Description of the Related Art
It has been generally known that print characteristics in a printer apparatus, as an image forming apparatus, are influenced and changed by the environment in which the printer apparatus is installed. The change in the print characteristics is mainly caused by change in temperature and humidity of the installed environment, change due to aging of the continuously used apparatus, component replacement in the apparatus, and the like. The change in the print characteristics causes change in the density and the tint of an output print product, and thus there is a problem that a stable print result cannot be obtained.
In a production market where print products are commercialized, achieving a stable print result is a highly important task. Thus, calibration (calibration processing) is executed to keep the variable print characteristics constant.
The calibration processing is executed so as to perform correction to achieve target print characteristics, defined in the printer apparatus in advance. The print characteristics include solid characteristics and halftone characteristics. As the calibration for the solid characteristics, for example, laser emission intensity, a device voltage, and the like at the time of image forming may be adjusted to maintain constant solid density of an image to be printed. As the calibration for the halftone characteristics, for example, a gradation correction look up table (LUT) is updated based on the result of a test print to maintain constant halftone density of an image to be printed.
The calibration processing is basically executed according to an instruction from a user. Thus, the calibration is executed at timing decided by the user, and thus might not be executed at appropriate timing. For example, when the calibration is not executed for a long period of time, a problem arises that the change in the print characteristics in the printer apparatus accumulates, and thus an appropriate print result cannot be obtained.
A technique for uniformly managing an execution timing of the calibration in the printer apparatus has been discussed (see Japanese Patent Application Laid-Open No. 2000-318266). In a technique discussed in Japanese Patent Application Laid-Open No. 2000-318266, time elapsed after the calibration has been executed is managed, and a warning prompting the user to perform the calibration is displayed when a predetermined time or more elapses.
In a system in which printing is performed by using the printer apparatus and a print server (image processing controller) connected to the printer apparatus, the calibration processing can be independently executed in each apparatus. Each calibration processing is executed to correct the print characteristics of the printer apparatus.
The calibration processing in the print server is executed after the calibration processing is executed in the printer apparatus to achieve higher accuracy. Thus, an appropriate effect can only be obtained when the print characteristics in the printer apparatus are kept constant.
Thus, for example, when the execution timing of the calibration processing in the print server is managed based on the elapsed time, the appropriately corrected print result might not be obtained when the calibration processing is executed in the printer apparatus. There are some printer apparatuses that can execute processing of automatically correcting the print characteristics in the printer apparatus, in addition to the calibration that the user arbitrarily performs. Also in such a case, the appropriately corrected print result might not be obtained. In view of this situation, the following method has been also discussed. Specifically, whether to execute the calibration processing in the print server is determined when the calibration processing is executed in the printer apparatus. Thus, an instruction to execute the calibration is issued to the print server when required.
In the system in which the printing is performed by using the print server connected to the printer apparatus, usually, the printer apparatus and the print server are each provided with an independent power source. Thus, it is also possible to operate the printer apparatus only or the print server only. When the setting of the print server is changed, the print server may need to be restarted so that the content of the change is reflected in the system. The print server turned OFF or being restarted as described above cannot receive the execution instruction for the calibration from the printer apparatus.
The following technical approach can be employed. Specifically, a unit that determines whether the execution instruction for the calibration is successfully transmitted may be provided, and the printer apparatus may repeat the transmission of the execution instruction until the print server receives the execution instruction. Unfortunately, the technical approach is highly inefficient because when the print server receives the execution processing is unclear.
Power saving, in electronic devices, is under vigorous development due to factors such as regulation that has been recently enacted in Europe. Thus, print servers that transition to a low power mode, such as a sleep mode, have been increased. In such a low power mode, a control is performed so as to prevent the print server from needlessly recovering from the low power mode. Thus, a received external access is ignored except for the access such as a print job that requires recovering of the print server.
The calibration processing needs not to be executed in the print server even when the calibration processing is executed in the printer apparatus, unless the print server is used immediately. Specifically, the calibration processing might be executed in the printer apparatus before the print server, recovered from the low power mode to execute the calibration, is used. Thus, it might be necessary to execute the calibration again in the print server. Thus, in many cases, a control is performed so that the print server in the low power mode ignores the execution instruction for the calibration to the print server, from a view point of power consumption.
All things considered, the print server might not be able to execute the calibration, even when the execution instruction for the calibration is issued to the print server from the printer apparatus. Thus, the appropriately corrected print result might not be obtained.